Double begonia, also known as wax begonia and begonia semperflorens, is a profusion bloomer of the Begoniaceae genus.
With its large, gorgeous, double flowers of vivid colors, it is an eye-catching point wherever it is planted: in a flower bed, patio planter, or a container on the terrace or window sill.
Despite the increasingly diverse offer of summer flowering plants, the double begonia has remained one of the most beloved species among gardeners worldwide.
What Is Double Begonia?
Double begonia was created by cultivating single begonia to obtain a plant with full, multi-layered flowers. It grows in the low shrub form up to 15 inches high and has upright, watery, and brittle stems on which glossy, smooth, irregular-shaped leaves grow.
From the second half of spring until the first frost, male and female double begonia flowers appear on the tops of the stems because the plant is a monocotyledon. The male flowers have a diameter of 3 to 5 inches. The females are inconspicuous, small, and single.
After pollination, the female flowers produce triangular boxes with tiny double begonia seeds. The flowers come in a wide range of colors and shades, including almost everything except blue.
– Double Begonia: Annual or Perennial?
Double flowering begonia belongs to the group of so-called tuberous begonias. The aboveground part develops from the tuberous, fleshy root and in one season goes through all stages from sprouting, flowering, seed production to wilting and dying in late autumn.
Due to this property, the plant is often grown as an annual in the areas with cold winters in USDA climate zones 3 to 7.
However, if stored during the winter and replanted in the spring, the tuber will give new shoots, leaves, and flowers, which means that the double begonia can be treated as a perennial that will decorate your garden or balcony for years.
You can keep the plant in the vegetative phase over the winter if you bring it into the house in a warm and bright place at the end of summer. The plant will not bloom since there is not enough daylight during the winter, but it will keep the leaves.
Tubers, sensitive to low temperatures and moisture, can remain outside in the ground only in climate zones 8 to 11. For all those who live outside these zones growing double begonias as annuals or perennials is a matter of choice!
Double Begonia Care
Double blooming begonias thrive in fertile but well-drained soil, whether you plant them in the garden or pots. Since it likes a mild acid reaction of the ground, you can plant it in a ready-made mixture for azaleas or African violets. In the absence of such substrates, you can grow it in a homemade blend combining equal parts of standard potting soil with perlite and peat moss. Instead of peat moss, you can use compost which also gives the soil acidity and increases nutrition.
It is a common belief that begonias are plants that love moisture and shade. Although this is partly true, it does not mean that the substrate should be constantly wet and the plant in deep shade. Therefore, if you want a healthy begonia that blooms profusely, pay special attention to watering!
Begonia likes to be watered frequently but only if it grows in a well-drained substrate in which water does not accumulate around its tuber. The surface layer of the substrate at a depth of at least one inch should be dry before watering the plant again.
When watering your double begonia, use a can with a beak and water always along the edge of the pot, avoiding wetting the leaves. After watering, make sure that excess water has accumulated in the tray and remove it immediately. Never allow the root to be near stagnant water in the trey!
Optionally, you can use a bottom watering strategy! Instead of pouring water from above, put the pot with the begonia in another vessel half filled with water. Let the substrate absorb water for 10 minutes. Then you could take out the plant, let it drain, and put it back in place.
The combination of light and shade is ideal for growing double bloom begonia. The east or north window on which the plant will get two or three hours of direct morning sunlight stimulates the development of flowers.
Move it a few feet away from the south or west window if they are not shaded. The delicate leaves of the double begonia cannot withstand the bright midday sun, so provide it with a position in the house or garden that is protected in the hottest part of the day.
On the other hand, a plant, constantly in the shade, gives many leaves but few flowers. Therefore, if you grow it indoors, in a spot with insufficient lighting, you can add a fluorescent lamp in the absence of natural light.
Native to the tropical zone of Brazil and Mexico, begonias have zero tolerance to low temperatures. Already at a temperature of 55 F, its leaves and flowers begin to decline. Unfortunately, the temperature in the northern hemisphere is below that value for almost half a year. Therefore, the plant outdoors often dies as early as the end of September.
If you grow double begonias in pots and want to keep them over the winter, bring them into the house at the end of August since the optimal temperature ranges from 65 to 75 F.
All in all, double begonia more easily tolerates high than low temperatures. Provided it is not detected by the blazing summer sun and watered regularly, it can withstand temperatures about 10 degrees above 75 F.
One of the reasons why keeping a begonia in the vegetative phase during the winter can be challenging is the high humidity level of 50 to 80 percent, necessary for its cultivation. The simple spraying of the leaves that helps many tropical plants does not apply to begonias because they are prone to fungal diseases.
So all you have to do is use a humidifier or place the plant on a pebble tray. Dry air in combination with small amounts of light during the winter might destroy this plant.
Double begonia has an accelerated metabolism and passes the phase from a leafless tuber to a flowering plant within 12 to 14 weeks. Therefore it needs a lot of energy and nutrients.
Regardless of the soil additives such as compost that form the basis for feeding this plant, it will grow much better and bloom more abundantly if you feed it regularly from spring to autumn.
Although you can use liquid, balanced fertilizers with an NPK ratio of 10:10:10, as a flowering plant, the double begonia plant responds better to fertilizers with an increased content of phosphorus that stimulates the development of buds and flowers. Thus, it is ideal if you combine these two fertilizers.
At the beginning of the growing season, fertilize it once a month with a balanced fertilizer, but in the second half of May, add fertilizer with N-P-K ratio 15:30:15, intended for flowering plants.
Always add the fertilizer after watering the plant, never in a dry substrate! In addition, as a precaution, start supplementation with a diluted concentration (1:2) relative to the recommended to avoid sudden or inadequate nutrient intake.
Regular care of double begonias involves removing damaged or withered foliage as well as wilted flowers. You could pinch the tips once a month to encourage a more compact shape. If the plant bends to one side towards the light source, prune the long shoots and rotate the plant every week.
Its fragile stems can be broken by strong winds or drafts, particularly when carrying large and heavy flowers. If it happens, remove them immediately so that the plant does not waste energy on the damaged parts since the plant will quickly replace them with new shoots and flowers.
Double begonias can be propagated by dividing tubers, stem cuttings, leaf cuttings, and seeds. Below we will explain, step by step, the first two methods because they are simple, effective, and more commonly applied.
– Tubers Dividing
The round tuber of the double begonia is concave on one side and belly-shaped on the other. In February, from the hollow part, a tooth-like growth appears. Older tubers always give several such growths, and you can grow each as a separate plant.
- Cut the tuber in half with a sterile knife providing that each part has to have at least one tooth.
- Leave the parts, at least a few days in a warm room to dry.
- When the cut hardens and forms a scab, you can plant it in a small pot with a moist mixture of soil and perlite.
- Turn the tooth up and cover with a layer of the mixture at least one inch thick.
- Place a pot in a warm, bright room and keep the substrate moderately moist.
- In the next seven to fourteen days, the tooth will emerge from the substrate and grow as a new plant.
– Stem Cuttings
To propagate double begonia by stem cuttings, you need at least 3 inches long stem without flowers or buds and at least three nodes.
- Cut it at an angle below the third node.
- Remove all lower leaves, leaving only two or three leaves at the top.
- Immerse the lower part of the stem in rooting hormone and then insert into a container filled with moist compost, peat moss, or a combination of soil and perlite.
- Cover the bowl with a plastic bag but so that the bag does not touch the leaves.
- Place the setup in a warm and bright position.
- Ventilate every few days and keep the soil moist.
Gradually, the stems will develop roots that will later form a small tuber. The plant propagated from stem cuttings should spend the winter in the house protected from low temperatures. It is best to leave it in the same pot during the next growing season.
Common Problems When Growing Double Begonia
– Double Begonia Not Blooming Issue
If you place the begonia in a position where it does not get enough light, the result will be a plant without flowers! Furthermore, if the plant does not get enough water by the inertia of the life cycle, it will give flowers, but they will be small and few. That is why the choice of position and proper watering is the key to care for this plant.
There is an easy way to encourage the plant to produce even more flowers. With each large male flower, the plant develops smaller, female ones.
If you remove the female one, you will stimulate the plant to produce a new pair of flowers!
Take advantage of the fact that the plant tends to provide enough flowers for pollination and seed production!
– Powdery Mildew
Powdery mildew is a fungal disease that often affects double begonias. Shady position, humidity, or poor air circulation between the leaves favor its development. You will recognize it by the floury white clumps on the leaves.
Although it will not vitally endanger the plant, it will weaken it and make it look sick and neglected. Therefore, remove all affected leaves and treat the plant with a mild fungicide. Furthermore, pay attention to the watering schedule as well as the place where the plant grows. Sometimes just a bit more sunlight is enough to make the fungus disappear.
Here is everything we’ve learned about the proper care of double begonia.
- Combine morning lights and shade for the rest of the day.
- Water when the surface of the substrate dries to a depth of one inch. Be careful and not overdo it, as the tuber tends to rot.
- Plant the tuber in porous but nutritious soil that drains water well. The ideal combination is equal parts potting soil, peat moss, and perlite.
- When the frost destroys the aboveground part, dig up the tuber, dry it and store it in a cool dark room. Bring potted plants into the house as soon as the night temperature drops below 55 F.
- You can overwinter begonia in the house if you provide it with plenty of light, the humidity of 50 to 80 percent, and a temperature of at least 65 F.
- Feed it once a month with diluted fertilizer intended for flowering plants from the end of May to autumn.
If you are looking for a plant adorned with large flowers in vivid colors for months, does not require much attention, and can grow in slightly shady positions, double begonia is the right choice for you.
Its cultivation will be an effortless pleasure if you follow the tips we’ve listed above.
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